koreth@ssyx.ucsc.edu (Steven Grimm) (10/26/87)
Keywords: In article <1471@brahma.cs.hw.ac.uk> neil@cs.hw.ac.uk (Neil Forsyth) writes: > >Neochrome uses screen interrupts to get more colours on the screen & The Pawn >(Magnetic Scrolls Graphic Adventure) uses them to mix low and medium resolution >modes on the screen. I have done both but would like to use this technique to >create segmented video ram ie. Non continuous video RAM. Anyone got any ideas? > I don't think it can be done. The video address counter variable ($FF8205 -- why they put it on an odd boundary is beyond me) is read-only; its writable counterpart looks like it's only accessed at the beginning of a display. The "LCD" demo circulating on BBSs nowadays does manage to put some graphics above the normal top of the screen (but it looks really bad) so it may be possible to tweak those variables. I wouldn't count on it working reliably, though. Oh, and the address counter is three bytes, FF8205, FF8207, and FF8209, MSB to LSB. Let us know what you come up with... +New! Improved! Now 100% Artificial-+-+-----------------------------------+ |# # @@@ **** &&&&& $$$$$ % %| |Steven Grimm | |# # @ @ * * & $ % %+-+ ARPA: koreth@ucscb.ucsc.edu | |### @ @ **** &&&& $ %%%%%| | UUCP: ...!ucbvax!ucscc!ssyx!koreth| |# # @ @ * * & $ % %+-+ ______________________________| |# # @@@ * ** &&&&& $ % %| | |"Let's see what's out there."| +-----with NutraSour(TM)! No natural colors or preservatives!------------+